Re: [PATCH bpf-next 1/4] bpf: crypto: Use the correct destructor kfunc type

With CONFIG_CFI_CLANG enabled, the kernel strictly enforces that
indirect function calls use a function pointer type that matches the
target function. I ran into the following type mismatch when running
BPF self-tests:

   CFI failure at bpf_obj_free_fields+0x190/0x238 (target:
     bpf_crypto_ctx_release+0x0/0x94; expected type: 0xa488ebfc)
   Internal error: Oops - CFI: 00000000f2008228 [#1]  SMP
   ...

As bpf_crypto_ctx_release() is also used in BPF programs and using
a void pointer as the argument would make the verifier unhappy, add
a simple stub function with the correct type and register it as the
destructor kfunc instead.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
  kernel/bpf/crypto.c | 7 ++++++-
  1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 94854cd9c4cc..b703b1d1c282 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c

@@ -261,6 +261,11 @@ __bpf_kfunc void bpf_crypto_ctx_release(struct bpf_crypto_ctx *ctx)
  		call_rcu(&ctx->rcu, crypto_free_cb);
  }
  
+__bpf_kfunc void __bpf_crypto_ctx_release(void *ctx)

+{
+	bpf_crypto_ctx_release(ctx);
+}
+
  static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx,
  			    const struct bpf_dynptr_kern *src,
  			    const struct bpf_dynptr_kern *dst,

@@ -368,7 +373,7 @@ static const struct btf_kfunc_id_set crypt_kfunc_set = {
  
  BTF_ID_LIST(bpf_crypto_dtor_ids)
  BTF_ID(struct, bpf_crypto_ctx)
-BTF_ID(func, bpf_crypto_ctx_release)
+BTF_ID(func, __bpf_crypto_ctx_release)
  
  static int __init crypto_kfunc_init(void)
  {